An effective stabilizing system for PVC/clay composites has been established in this work. Different types of stabilizers i.e. organo-tin, calcium/zinc, barium/zinc stabilizers and an epoxy co-stabilizer were investigated. It was found that the combination of the organo-tin stabilizer and the epoxy co-stabilizer was the most effective stabilizing system for PVC/clay composites. Different grades of Cloisite nano-clays supplied by Southern Clay Products Inc. were investigated. It was found that natural montmorillonite (Cloisite Na) did not cause premature degradation of PVC, however it was difficult to disperse in the PVC matrix due to its hydrophilicity. Ammonium modified nano-clays such as Cloisite lOA and Cloisite 30B were compatible with PVC, and both nano-clays were much easier to disperse in PVC than Cloisite Na. Cloisite lOA seriously accelerated the degradation of PVC, but PVC/Cloisite 30B system showed much better thermal stability. The effects of processing conditions on PVC/clay composite structure were investigated. The composite structure was characterized by both TEM and XRD. PVC/Cloisite Na nano-composites could not be successfully prepared no matter what processing conditions were used. Partially exfoliated and intercalated PVC/Cloisite 30B nano-composites could be prepared by melt compounding. The particulate structure of PVC resin affected the distribution of clay, which could be improved by increasing the processing temperature. Almost fully exfoliated PVC/Cloisite 30B nano-composites were successfully prepared by a solution process in tetrahydrofuran, and the plasticizer migration resistance ofthis composite was significantly improved. Phosphonium modified clays were also prepared successfully. They showed better thermal stability than ammonium modified clays, but the drying conditions still need to be optimized to produce a dispersable clay powder. Other commercial fillers for PVC such as calcium carbonate and hydrotalcite were compared with Cloisite 30B. It was found that Cloisite 30B provided the best improvement in plasticizer migration resistance, but decreased the tensile properties. Possible mechanisms were proposed. It is interesting to find that PVC crystallization in the clay galleries can occur during annealing that increased the clay gallery spacing. There seemed to be orientation of the newly formed crystallites, and two types of orientation have been proposed.

No description available.

No description available.

The recycling of plastics tends to lag behind other packaging materials. The research investigates opportunities to improve the capture of valuable packaging polymers and to preserve their specification during recycle operations, thus increasing second user opportunity. The legislative and policy drivers on the sustainable use of plastics are described and discussed with particular reference to achieving sustainability, reuse and recycle of healthcare packaging materials. Four strategic methods of achieving improvements in sustainability, reuse and recycle are developed to represent aspects of sorting of materials, collection of recyclables, replacement of unsustainable packaging materials and measurement of the environmental impacts of packaging and changes in packaging, using examples of packaging from GlaxoSmithKline consumer healthcare and medical products. The use of radio frequency identification methodology as a means of separating high quality plastics and individual reusable devices from mixed waste streams has been developed and trialled under simulated materials recycling and separation conditions. The use of Reverse Vending Machines (RVM's) designed to capture high quality polyethylene terephthalate polymers is described along with results of successful trials on this method of capture in the out of home consumption sector. Recovered material is suitable for reuse in food grade applications after reprocessing. A novel biodegradable packaging material has been successfully developed from sources of green waste as an alternative to existing polymer packaging materials for transport of vaccines, and provides results that are extendable to the replacement of other types of packaging over a wide range of consumer goods. The material also offers intangible benefits to a business in terms of claims that can be made within a corporate social responsibility (CSR) report. Life cycle analysis methodologies have been used to illustrate the environmental benefits that can be achieved by reuse of polypropylene as an example of a widely used packaging polymer with potential for reuse in other industrial sectors. The implications of the results obtained in this work should be of value in the future eco-design of polymer products designed to make end-of-life recovery and recycle more efficient and environmentally beneficial.

With the upcoming technology available today, for the conversion of waste to useful products, research in the area of thermal degradation has gained particular attention. However, the wide product distribution and the high temperatures employed in such a process makes catalytic degradation a more promising solution to the problem of plastic waste. In catalytic degradation, lower temperatures are employed and the product distribution is narrow. This eliminates the need for further processing of the fuel in order to upgrade its quality. The aim of this work is to carry out a systematic study of various industrial catalysts in a catalytic degradation system. More specifically, the influence on the yield to liquid fuel, product distribution and hence; quality and regeneration ability of the catalysts. The catalytic degradation of polyethylene over various microporous materials, zeolite-based and clay-based catalysts, was studied in a semi-batch reactor. From the zeolites, ZSM-5 resulted mostly in gaseous products and almost no coking due to its shape selectivity properties. Commercial cracking catalysts fully degraded the polymer resulting in higher liquid yield and lower coke content than their parent ultrastable Y zeolite. This confirmed the suitability of such catalysts for a polymer recycling process and its commercialisation potential, as plastic waste could be co-fed into a refinery cracking unit. Clays, Saponite and Zenith-N, a montmorillonite, and their pillared analogues were less active than zeolites, but could fully degrade the polymer. They showed enhanced liquid formation, due to their mild acidity, and lower coke formation. Regenerated pillared clays showed practically the same performance as fresh samples, but their original clays' performance deteriorated after removal of the formed coke. Although performance of the regenerated saponite was satisfactory, with the regenerated Zenith-N the structural damage was so extensive that plastic was only partly degraded.

Emulsion polymerisation is a process of considerable technological and industrial significance. The process presents many challenges in respect to design, optimisation and multi-objective distribution control. The quality of latex is determined by the final product properties, Le. viscosity, mechanical strength and film-forming ability, which are in turn a function of the latex attributes of PSD and MWD. This motivates an inferential control scheme utilising these distributions. This research addresses model development and controllability analysis towards model-based control. A population balance model for PSD and MWD is developed. The PSD information is incorporated via a one-dimensional population distribution of the polymer particles with respect to their size, in conjunction with a population distribution of the total live polymer radicals/particle. MWD information is incorporated via one-dimensional population distributions of the live radicals and dead polymer chains with respect to their length (in different sized particles). The model solution is facilitated by a number of algorithmic developments, including a decomposition algorithm coupled with a multi-level discretisation for PSD and the application of the method of moments for MWD. This model is compared to extensive experimental data for its validation. Improvements in the form of a twodimensional version of this model enable better prediction of compartmentalisation and hence the growth rates, thereby improving model match with experiments. This work presents a study into the simultaneous controllability of PSD and MWD, assessed through an experimental sensitivity analysis on the main process manipulations: initiator, eTA, monomer and surfactant. The work analyses the practical limitations on the attainability of PSD and MWD. The range of experiments carried out clearly indicates the operation of individual mechanisms in the simultaneous formation of PSD and MWD.

No description available.

The present work investigates the ability of several different epoxies to be toughened with the addition with 20 nm silica nanoparticles (nanosilica). The formation of ‘hybrid’ epoxy polymers, containing both silica nanoparticles and carboxyl-terminated butadiene-acrylonitrile (CTBN) rubber micro-particles, is also discussed. The structure/property relationships are considered, with an emphasis on the toughness and the toughening mechanisms. Particular attention was given to an anhydride cured diglycidyl ether of bisphenol-A (DGEBA) system where the fracture energy increased from 83 to 204 J/m2 with the addition of 20 wt. % of silica nanoparticles. Plastic shear bands followed by debonding of the matrix from the silica nanoparticles, and subsequently plastic void growth of the epoxy were found to be the operative toughening mechanisms. The largest increases in toughness observed were for the ‘hybrid’ materials where a synergistic behaviour on the fracture energy. A maximum fracture energy of 1051 J/m2 was measured for a ‘hybrid’ epoxy polymer containing 10 wt. % silica nanoparticles and 9 wt. % rubber micro-particles. The toughening mechanisms for such systems were postulated to be rubber-particle cavitation, shear band yielding and void growth and debonding and plastic void growth of the nanosilica necklaces. Ultimately, these polymers are intended to be used as matrices in fibre-reinforced composites. Therefore, resistance to delamination as fibre-composites has been examined for such modified epoxies. The interlaminar fracture energies for the fibrecomposite materials were found to increase even further by a fibre bridging toughening mechanism. However, the fibre-matrix adhesion is shown to be an important parameter. The present work has extended an existing model to predict the toughening effect of the nanoparticles in the epoxy polymer. There was excellent agreement between the predictions and the experimental data for epoxy containing the silica nanoparticles, and for epoxy polymers containing rubber or coreshell particles. Inferences have been made about the toughenability of the epoxy being sensitive to particle-matrix adhesion and the ability for the matrix to shear yield.

No description available.

In water filtration processes, the employment of polymeric membranes has become increasingly popular over the past few decades. However, the application of membrane processes is often limited due to the low fluxes and membrane failures caused by fouling and low membrane durability, which eventually leads to high operating costs in comparison with conventional processes. These limitations could be overcome by the development of high performance membranes with enhanced properties through a cost effective method. This thesis explores the preparation of high performance poly(vinylidene fluoride) (PVDF) membranes with the use of inorganic silica particles via a conventional immersion precipitation method and from an amphiphilic graft copolymer. A technique to improve the performance of PVDF membranes fabricated via immersion precipitation has been developed, which involves using inorganic silica (SiO2) particles during the preparation of the dope solution, followed by subsequent acid or alkaline treatments of the resultant membranes. By removing the SiO2 particles from the membrane substrates using either an acid or alkaline treatment, the resultant membranes exhibit an interconnected porous structure accompanied by a significant improvement in the water permeability. Due to the poor mechanical strength demonstrated by the NaOH treated membranes, detailed investigations of the stability of PVDF membranes in NaOH solutions are carried out on hollow fibre membranes prepared from different raw materials. Hollow fibre membranes exhibit different degrees of chemical degradation upon exposure to a sodium hydroxide solution under various conditions. Also, a simplified method has been developed as a cost effective way for the preparation of PVDF membranes with improved hydrophilicity, fouling resistance and water permeability from the amphiphilic graft copolymer, PVDF-g-PEGMA, which has a PVDF backbone and poly(ethylene glycol) methyl ether methacrylate (PEGMA) side chains. By eliminating three common steps involved during the conventional preparation method, the use of chemicals and energy can be substantially reduced.